Elevator systems include various devices for controlling movement of an elevator car. Under normal operating conditions, the elevator machine is responsible for controlling movement of the elevator car. Occasionally, an undesirable over speed condition may exist. Elevator systems include governor devices that operate auxiliary brakes or safeties to stop elevator car movement under such circumstances. A variety of such brakes are known.
Most safeties engage the guiderail along which the elevator car travels. Some safeties include rollers while others include wedge-shaped components that engage the guiderail to apply a braking force for preventing movement of the elevator car. Some safeties include some form of spring or biasing element to urge the brake components into engagement with the guiderail. For example, a set of disk-shaped springs are stacked under compression for urging the brake member in a direction toward the guiderail when braking engagement is desired. One drawback associated with such spring arrangements is that the force applied by the springs varies with the amount of spring deflection. A more consistent force application would be an improvement. Another drawback associated with such spring arrangements is the hysteresis that occurs because of internal friction between the disks and the friction associated with contact between the disk surfaces and the brake member. Eliminating such hysteresis would be an improvement.